1. Field of the Invention
This invention relates to a method for producing protein hydrolyzates from animal and/or vegetable starting materials by comminuting and mashing the comminuted starting materials into a pumpable mass, decomposing the mashed starting materials in an electric discharge gap and separating the aqueous phase of the decomposition from solid and water-unmixable residues.
Protein-containing residues from industrial or manual processing of agricultural products as well as vegetable raw materials are valuable raw products due to the contained ingredients. However, a problem is frequently the cost-effective and simple recovery of these ingredients. In particular offal, such as skins, hairs, bristles, feathers, bones, meat parts, blood, etc., largely defies simple and cost-effective further processing as far as their ingredients are concerned. The contained proteins are a valuable source of raw materials hitherto utilized only to a small extent.
2. Description of the Related Art
The inventive method develops a technique known from DE 42 31 914 A1. This print describes a method for producing protein hydrolyzates from animal and/or vegetable substrates by comminuting the substrates, heating the comminuted substrate, mashing the heated substrate into a pumpable mass, decomposing the mashed substrate by means of electric discharges and separating the aqueous phase of the decomposition from solid and water-unmixable liquid residues wherein the temperature is held below the coagulation temperature of protein during the entire method and mashing is performed with aqueous hydrolyzate phase obtained from the decomposition. This method has its advantages but is still capable of being improved with respect to energy consumption and the processing of the obtained products. In particular the separation of obtained protein hydrolyzates from solid and water-unmixable liquid residues is elaborate and cost-intensive. Although one can improve the separation and subsequent filtration of the obtained hydrolyzate solution by suitable pretreating the starting materials, this is an additional step with additional costs.
DE-A 37 13 179 A1 further discloses a method for recovering gelatin and products containing it wherein collagen-containing starting material is decomposed in an aqueous medium with the aid of electric current. The collagen containing starting material used is offal. Decomposition takes place with an electric discharging current with short discharge pulses. The method obtains a collagen-containing material which is used in particular as glue.
The discharge apparatus used in this known method is known in the art and has been described for a variety of purposes, including the abovementioned. For the discharge technology reference is furthermore made to DE-PS 12 37 541 and 19 46 267 and to DE-OS 16 67 029, 17 92 572, 29 07 887 and DE 31 16 623 A1 and also to the statements in DE 37 13 179 A1.
Finally, DE-OS 27 50 149 discloses a method for producing keratin-like protein wherein keratin is hydrolyzed with saturated steam under pressure. The process conditions are quite drastic and lead to high costs and a chemically changed product.
The objectives of the invention is a method for separating the proteins contained in animal and vegetable raw materials, in particular offal and vegetable agricultural raw products and waste, in simple, cost-effective and largely pure fashion.